A system of this kind is known from DE 102 10 941 A1. Here, the running gear of the transport carriage is constructed to be substantially symmetrical to a centre plane which extends centrally between the two rails on which the running gear travels. The angle formed between the shaft and the two rails is 90° and cannot be varied. This is a two-track vehicle which is suitable in particular for relatively heavy loads. However, the following disadvantage is associated with it: once any transport carriage which has guided an object through the system has been unloaded, it has to be returned again to a starting position, in which it is loaded with a new object. This returning of the transport carriages cannot generally be performed on the same rails as the “outward” movement; rather, in addition to the “outward” rails, two further rails have to be provided on which the “return” path is then performed. These two rails necessarily occupy a relatively large space in the room where the system is located. However, there is frequently not much space available, and in all cases it comes at a cost.
DE 10 2008 010 400 A1 discloses a system for dip treating objects in which the transport system is constructed in the manner of an overhead track. This is a single-rail system. The individual transport carriages moved on the single rail are provided with a telescope-like securing means at the lower end whereof a rotary shaft is provided. This projects freely, pointing away from the rail on which the transport carriages can travel, and bears a mounting frame for an object that is to be treated. The securing means is able to rotate about a vertical axis with the shaft and the mounting frame, with the result that the transport carriages occupy less space during the return from the unloading station to the loading station. In all sections of the system, however, the transport carriages are single-track and so less suitable for receiving large loads.
An object of the present invention is to further develop a system of the type mentioned at the outset such that there is less space requirement, in particular on the return path from the unloading station to the loading station, while retaining the bearing capacity of the individual transport carriages.